fix return format

NLP_model/chatbot.py

@@ -110,7 +110,7 @@ You have to use core knowledge and conversation history to chat with users, who
 
 Return Format:
 Respond in friendly, natural, concise and use only English like a real tour guide.
-Always return in HTML format that telegram can render to special format.
+Always use HTML tags (e.g. <b> for bold) so that Telegram can render the special formatting correctly.
 
 Warning:
 Let's support users like a real tour guide, not a bot. The information in core knowledge is your own knowledge.
@@ -156,7 +156,7 @@ def get_chain():
             text_key="text"
         )
         
-        _retriever_instance = vectorstore.as_retriever(search_kwargs={"k": 7})
+        _retriever_instance = vectorstore.as_retriever(search_kwargs={"k": 6})
         logger.info(f"Pinecone retriever initialized in {time.time() - start_time:.2f} seconds")
         return _retriever_instance
     except Exception as e: